CN114333665B - Light emitting diode driving circuit - Google Patents
Light emitting diode driving circuit Download PDFInfo
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- CN114333665B CN114333665B CN202210128524.3A CN202210128524A CN114333665B CN 114333665 B CN114333665 B CN 114333665B CN 202210128524 A CN202210128524 A CN 202210128524A CN 114333665 B CN114333665 B CN 114333665B
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Abstract
The invention discloses a light emitting diode driving circuit, which comprises a first pulse circuit, a first light emitting control transistor, a light emitting diode, a sensing circuit and a second light emitting control transistor. The sensing circuit comprises a first sensing transistor and a second sensing transistor which are arranged at two ends of the light emitting diode, and the light emitting state of the light emitting diode can be dynamically detected by the control of the sensing circuit, so that the light emitting diode driving circuit is properly compensated, and the required display effect is achieved.
Description
Technical Field
The present invention relates to a light emitting diode driving circuit, and more particularly, to a light emitting diode driving circuit with a sensing circuit for dynamically detecting a status of a light emitting diode in a light emitting region of the light emitting diode.
Background
In the led display panel, a related driving circuit is designed to drive the leds in each pixel, but when the panel driving circuit is subjected to a temperature change, the forward voltage (forward voltage) will also change, which will affect the passing current and the operation efficiency. When the above-mentioned influence occurs, the light emitting effect of the light emitting diode is also affected, so that the display effect of the whole display picture is affected.
Aiming at the influence caused by temperature change, the display device of the light-emitting diode can correspondingly compensate according to the change, so that the driving voltage and the current passing through the light-emitting diode can reach the required standard, and the light-emitting result of each pixel can meet the expectations. However, in order to perform the corresponding compensation, the actual operation state of the light emitting diode and the driving circuit thereof must be controlled to provide the corresponding compensation method. However, when the display panel displays a screen, the conventional driving circuit cannot dynamically detect the light emitting diode to understand the actual operation state, and it is difficult to properly compensate for the operation of the light emitting section, which still has a considerable problem in displaying the screen.
In view of the foregoing, the operation of the existing led driving circuit in led state detection and compensation still has considerable drawbacks, so the present invention improves the drawbacks of the prior art by designing an led driving circuit to solve the problems of the prior art, thereby enhancing the industrial implementation and utilization.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a light emitting diode driving circuit, which solves the problem that the conventional light emitting diode driving circuit cannot perform dynamic detection.
According to the above-mentioned object, an embodiment of the present invention provides a light emitting diode driving circuit, which includes a first pulse circuit, a first light emitting control transistor, a light emitting diode, a sensing circuit, and a second light emitting control transistor. The first pulse circuit is coupled to the data line and the scan line, the output end of the first pulse circuit is coupled to the control end of the first driving transistor, the first end of the first driving transistor is coupled to the first node, and the second end of the first driving transistor is coupled to the second node. The first end of the first light-emitting control transistor is coupled to the first voltage source, the second end of the first light-emitting control transistor is coupled to the first node, and the control end of the first light-emitting control transistor is coupled to the first light-emitting signal line. The first end of the light emitting diode is coupled to the second node, and the second end of the light emitting diode is coupled to the third node. The sensing circuit comprises a first sensing transistor and a second sensing transistor, wherein the first sensing transistor is coupled to the second node, the control end of the first sensing transistor is coupled to the first sensing grid signal line, the second sensing transistor is coupled to the third node, and the control end of the second sensing transistor is coupled to the second sensing grid signal line. The first end of the second light-emitting control transistor is coupled to the third node, the second end of the second light-emitting control transistor is coupled to the second voltage source, and the control end of the second light-emitting control transistor is coupled to the second light-emitting signal line.
In an embodiment of the invention, the driving circuit of the light emitting diode further includes a second pulse circuit, the second pulse circuit is coupled to the data line and the scan line, an output terminal of the second pulse circuit is coupled to the control terminal of the second driving transistor, a first terminal of the second driving transistor is coupled to the third node, and a second terminal of the second driving transistor is coupled to the first terminal of the second light emitting control transistor.
In an embodiment of the present invention, the first pulse circuit includes a pulse amplitude modulation (Pulse Amplitude Modulation, PAM) circuit coupled to the pulse amplitude modulation data line and the scan line, and the second pulse circuit includes a pulse width modulation (Pulse Width Modulation, PWM) circuit coupled to the pulse width modulation data line and the scan line.
In an embodiment of the present invention, the pulse amplitude modulation circuit includes a first transistor, a second transistor, a first capacitor, a third transistor, and a fourth transistor. The first end of the first transistor is coupled to the pulse amplitude modulation data line, the second end of the first transistor is coupled to the control end of the first driving transistor, and the control end of the first transistor is coupled to the scanning line. The first end of the second transistor is coupled to the power-off signal line, the second end of the second transistor is coupled to the fourth node, and the control end of the second transistor is coupled to the scan line. One end of the first capacitor is coupled to the fourth node, and the other end of the first capacitor is coupled to the second end of the first transistor. The first end of the third transistor is coupled to the fourth node, the second end of the third transistor is coupled to the first node, and the control end of the third transistor is coupled to the first light-emitting signal source. The first end of the fourth transistor is coupled to the fifth node, the second end of the fourth transistor is coupled to the power-off signal line, and the control end of the fourth transistor is coupled to the first light-emitting signal source.
In an embodiment of the present invention, the pwm circuit includes a fifth transistor, a sixth transistor, a second capacitor, a seventh transistor, an eighth transistor, a ninth transistor, a tenth transistor, and a third capacitor. The first end of the fifth transistor is coupled to the pulse width modulation data line, the second end of the fifth transistor is coupled to the fifth node, and the control end of the fifth transistor is coupled to the scanning line. The first end of the sixth transistor is coupled to the fifth node, the second end of the sixth transistor is coupled to the sixth node, and the control end of the sixth transistor is coupled to the seventh node. One end of the second capacitor is coupled to the scanning signal line, and the other end of the second capacitor is coupled to the seventh node. The first end of the seventh transistor is coupled to the seventh node, the second end of the seventh transistor is coupled to the sixth node, and the control end of the seventh transistor is coupled to the scan line. The first end of the eighth transistor is coupled to the seventh node, the second end of the eighth transistor is coupled to the reset signal line, and the control end of the eighth transistor is coupled to the start signal line. The first end of the ninth transistor is coupled to the sixth node, the second end of the ninth transistor is coupled to the control end of the second driving transistor via the eighth node, and the control end of the ninth transistor is coupled to the first light emitting signal source. The first end of the tenth transistor is coupled to the reset signal line, the second end of the tenth transistor is coupled to the eighth node, and the control end of the tenth transistor is coupled to the set signal line. One end of the third capacitor is coupled to the reset signal line, and the other end of the third capacitor is coupled to the eighth node.
In an embodiment of the invention, when the led driving circuit is in the static detection interval, the first light emitting control transistor, the first sensing transistor and the first driving transistor are turned on, and the second light emitting control transistor, the second driving transistor and the second sensing transistor are turned off to detect the current flowing through the first sensing transistor.
In an embodiment of the invention, when the led driving circuit is in the light emitting interval, the first light emitting control transistor, the first driving transistor, the second light emitting control transistor and the second driving transistor are turned on, and the first sensing transistor and the second sensing transistor are turned off, so that the led is turned on by passing current.
In an embodiment of the invention, when the led driving circuit is in the dynamic detection interval, the first light emitting control transistor, the second light emitting control transistor and the second driving transistor are turned off, and the first sensing transistor and the second sensing transistor are turned on to detect the current flowing through the first sensing transistor, the led and the second sensing transistor.
In an embodiment of the present invention, the dynamic detection section is performed while occupying a light-emitting section in the frame picture.
In the embodiment of the invention, the frame time of each frame of picture is adjusted according to the execution time of the dynamic detection interval.
In the embodiment of the invention, the dynamic detection interval is scattered to different frames for execution.
In an embodiment of the present invention, the first pulse circuit includes a pulse amplitude modulation (Pulse Amplitude Modulation, PAM) circuit coupled to the pulse amplitude modulation data line and the scan line.
In an embodiment of the present invention, a pulse amplitude modulation circuit includes a first transistor, a second transistor, a first capacitor, and a third transistor. The first end of the first transistor is coupled to the pulse amplitude modulation data line, the second end of the first transistor is coupled to the control end of the first driving transistor, and the control end of the first transistor is coupled to the scanning line. The first end of the second transistor is coupled to the power signal line, the second end of the second transistor is coupled to the fourth node, and the control end of the second transistor is coupled to the scan line. One end of the first capacitor is coupled to the fourth node, and the other end of the first capacitor is coupled to the second end of the first transistor. The first end of the third transistor is coupled to the fourth node, the second end of the third transistor is coupled to the first node, and the control end of the third transistor is coupled to the first light-emitting signal source.
In the above description, the led driving circuit of the present invention can achieve two detection modes of static detection interval and dynamic detection interval by setting the sensing circuit, and monitor the actual state of the led to compensate the actual state correspondingly. The dynamic detection section can detect in the operation section of the light emitting diode for light emission, achieves the effects of instant detection and compensation, and avoids the influence of the device on the operation of the light emitting diode driving circuit and the display effect of the display device under the temperature change.
Drawings
In order to make the technical features, contents and advantages of the present invention and the effects achieved thereby more obvious, the present invention will be described in detail below in terms of expression of examples with reference to the accompanying drawings:
fig. 1 is a schematic diagram of a driving circuit of a light emitting diode according to an embodiment of the invention.
Fig. 2 is a schematic diagram of a driving circuit of an led according to another embodiment of the invention.
Fig. 3 is a circuit schematic of a first pulse circuit according to an embodiment of the invention.
Fig. 4 is a circuit schematic of a first pulse circuit and a second pulse circuit according to an embodiment of the invention.
Fig. 5A is a schematic diagram of a static detection interval according to an embodiment of the invention.
Fig. 5B is a schematic diagram of a light emitting section according to an embodiment of the invention.
Fig. 5C is a schematic diagram of a dynamic detection interval according to an embodiment of the invention.
Fig. 6 is a waveform diagram of a driving circuit of an led according to an embodiment of the invention.
Fig. 7A is a diagram illustrating a relationship between a dynamic detection interval and a frame according to an embodiment of the present invention.
Fig. 7B is a schematic diagram of an adjusting frame according to an embodiment of the invention.
Fig. 7C is a schematic diagram of dynamic detection interval dispersion according to an embodiment of the present invention.
Wherein, the reference numerals:
10 light emitting diode driving circuit
C1 first capacitor
C2 second capacitor
C3 third capacitor
Data line
data_PAM pulse amplitude modulation Data line
data_PWM (pulse Width modulation) Data line
DB1 first pulse wave circuit
DB2 second pulse wave circuit
DC power signal line
EM1 first luminous signal line
EM2 second light-emitting signal line
I1, I2, I3 Current
LED (light emitting diode)
N1 first node
N2 second node
N3 third node
N4-fourth node
N5 fifth node
N6 sixth node
N7 seventh node
N8 eighth node
PPO (Power Point of sale) power cut-off signal line
RES reset signal line
SB sensing circuit
Scan Scan line
Scan1 first Scan line
Scan2 second Scan line
SG1 first sense gate signal line
SG2 second sense gate signal line
SWEEP scanning signal line
TD1 first drive transistor
TD2 second drive transistor
TEM1 first light-emitting control transistor
TEM2 second light emission control transistor
TS1 first sense transistor
TS2 second sense transistor
T1 first transistor
T2 second transistor
T3 third transistor
T4:fourth transistor
T5:fifth transistor
T6:sixth transistor
T7 seventh transistor
T8 eighth transistor
T9:ninth transistor
T10:tenth transistor
VDD: first voltage source
VS1 first sense signal source
VS2 second sense signal source
VSS second voltage source
VST-Start Signal line
Detailed Description
For the purpose of promoting an understanding of the nature, content and advantages of this invention and its advantages, reference should be made to the drawings and specific language used to describe the same in connection with the accompanying drawings, which are intended to illustrate and assist in the description, but not necessarily to the actual scale and arrangement of the invention, so that the invention should not be construed as limited to the actual scope of the claims.
In the drawings, the thickness or width of a substrate, panel, region, line, etc. is exaggerated for clarity. Like numbers refer to like elements throughout. It will be understood that when an element such as a substrate, panel, region or line is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. "connected" as used herein may refer to physical and/or electrical connection. Furthermore, "electrically connected," "coupled," or "coupled" may mean that there are additional elements between the elements. Furthermore, it will be understood that, although the terms "first," "second," "third," and the like may be used herein to describe various elements, components, regions, layers and/or sections, these should be used to distinguish one element, component, region, layer and/or section from another element, component, region, layer and/or section. Therefore, for descriptive purposes only and not to be construed as indicating or implying relative importance or a sequential relationship thereof.
Unless defined otherwise, all terms used herein have meanings commonly understood by one of ordinary skill in the art to which the present invention pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Fig. 1 is a schematic diagram of a driving circuit of a light emitting diode according to an embodiment of the invention. As shown in the drawing, the light emitting diode driving circuit 10 includes a first pulse circuit DB1, a first light emitting control transistor TEM1, a first driving transistor TD1, a light emitting diode LED, a sensing circuit SB, and a second light emitting control transistor TEM2. The first pulse circuit DB1 is coupled to the Data line Data and the Scan line Scan, and an output terminal of the first pulse circuit DB1 is coupled to the control terminal of the first driving transistor TD 1. The first pulse circuit DB1 receives the Data signal of the Data line Data and the Scan signal of the Scan line Scan, and outputs the driving signal of the light emitting diode LED to the first driving transistor TD1, and the first pulse circuit DB1 may be a pulse amplitude modulation (Pulse Amplitude Modulation, PAM) circuit, a pulse width modulation (Pulse Width Modulation, PWM) circuit, or a combination thereof, examples of which will be described in the following embodiments. The first light emitting control transistor TEM1 and the second light emitting control transistor TEM2 are disposed at two sides of the light emitting diode LED, and are respectively coupled to the first light emitting signal line EM1 and the second light emitting signal line EM2, and control signals of the first light emitting signal line EM1 and the second light emitting signal line EM2 control current to light the light emitting diode LED through the light emitting diode LED.
In the structure of the led driving circuit 10, the first terminal of the first driving transistor TD1 is coupled to the first node N1, and the second terminal of the first driving transistor TD1 is coupled to the second node N2. The first terminal of the first light emitting control transistor TEM1 is coupled to the first voltage source VDD, and the second terminal of the first light emitting control transistor TEM1 is coupled to the first node N1. The first end of the light emitting diode LED is coupled to the second node N2, and the second end of the light emitting diode LED is coupled to the third node N3. The first terminal of the second light emitting control transistor TEM2 is coupled to the third node N3, and the second terminal of the second light emitting control transistor TEM2 is coupled to the second voltage source VSS. The first voltage source VDD may be a high voltage source, and the second voltage source VSS may be a low voltage source.
The sensing circuit SB in the led driving circuit 10 includes a first sensing transistor TS1 and a second sensing transistor TS2, the first sensing transistor TS1 is coupled to the second node N2, and the second sensing transistor TS2 is coupled to the third node N3. The sensing circuit SB is coupled to two ends of the LED, and compensates the light emitting state of the LED by detecting the actual voltage actually passing through the LED, so as to obtain a better light emitting effect. The first end of the first sensing transistor TS1 is coupled to the first sensing signal source VS1, the second end of the first sensing transistor TS1 is coupled to the second node N2, and the control end of the first sensing transistor TS1 is coupled to the first sensing gate signal line SG1. The first end of the second sensing transistor TS2 is coupled to the second sensing signal source VS2, the second end of the second sensing transistor TS2 is coupled to the third node N3, and the control end of the second sensing transistor TS2 is coupled to the second sensing gate signal line SG2.
Fig. 2 is a schematic diagram of a driving circuit of an led according to another embodiment of the invention. As shown in the drawing, the light emitting diode driving circuit 20 includes a first pulse circuit DB1, a first light emitting control transistor TEM1, a first driving transistor TD1, a light emitting diode LED, a sensing circuit SB, a second pulse circuit DB2, a second driving transistor TD2, and a second light emitting control transistor TEM2. The same reference numerals and symbols denote the same or similar contents, and reference is made to the description of the foregoing embodiments, and the description thereof will not be repeated.
Unlike the previous embodiment, the led driving circuit 20 includes a first pulse circuit DB1 and a second pulse circuit DB2, the first pulse circuit DB1 is a Pulse Amplitude Modulation (PAM) circuit, and the second pulse circuit DB2 is a Pulse Width Modulation (PWM) circuit. The first pulse circuit DB1 is coupled to the pulse amplitude modulation Data line data_pam and the first Scan line Scan1 for transmitting the pulse amplitude control signal, and an output terminal of the first pulse circuit DB1 is coupled to the control terminal of the first driving transistor TD 1. The second pulse circuit DB1 is coupled to the PWM Data line data_pwm and the second Scan line Scan2 for transmitting the PWM control signal, and an output terminal of the second pulse circuit DB2 is coupled to the control terminal of the second driving transistor TD2. The first driving transistor TD1 is coupled between the first node N1 and the second node N2, and the second driving transistor TD2 is coupled between the third node N3 and the second emission control transistor TEM2.
The first light emitting control transistor TEM1 and the second light emitting control transistor TEM2 are disposed at two sides of the light emitting control transistor LED, and are respectively coupled to the first light emitting signal line EM1 and the second light emitting signal line EM2, and control signals of the first light emitting signal line EM1 and the second light emitting signal line EM2 control current to flow from the first voltage source VDD to the second voltage source VSS, so as to light the light emitting diode LED through the light emitting diode LED.
The sensing circuit SB in the led driving circuit 20 includes a first sensing transistor TS1 and a second sensing transistor TS2, wherein a first end of the first sensing transistor TS1 is coupled to the first sensing signal source VS1, a second end of the first sensing transistor TS1 is coupled to the second node N2, and a control end of the first sensing transistor TS1 is coupled to the first sensing gate signal line SG1. The first end of the second sensing transistor TS2 is coupled to the second sensing signal source VS2, the second end of the second sensing transistor TS2 is coupled to the third node N3, and the control end of the second sensing transistor TS2 is coupled to the second sensing gate signal line SG2. The sensing circuit SB dynamically compensates the light emitting state of the light emitting diode LED by detecting the actual voltage of the light emitting diode LED, similarly to the foregoing embodiment.
Fig. 3 is a schematic circuit diagram of a first pulse circuit according to an embodiment of the invention. Referring to fig. 1, the first pulse circuit DB1 in the led driving circuit 10 may be a Pulse Amplitude Modulation (PAM) circuit. As shown in the drawing, the first pulse circuit DB1 includes a first transistor T1, a second transistor T2, a first capacitor C1, and a third transistor T3. The first end of the first transistor T1 is coupled to the pulse amplitude modulation Data line data_pam, the second end of the first transistor T1 is coupled to the control end of the first driving transistor TD1, and the control end of the first transistor T1 is coupled to the Scan line Scan. The first end of the second transistor T2 is coupled to the power signal line DC, the second end of the second transistor T2 is coupled to the fourth node N4, and the control end of the second transistor T2 is coupled to the Scan line Scan. One end of the first capacitor C1 is coupled to the fourth node N4, and the other end of the first capacitor C1 is coupled to the second end of the first transistor T1. The first end of the third transistor T3 is coupled to the fourth node N4, the second end of the third transistor T3 is coupled to the first node N1, and the control end of the third transistor T3 is coupled to the first light emitting signal source EM1.
In the present embodiment, the led driving circuit 10 is a eight-transistor-capacitor (8T 1C) driving circuit structure, and the first pulse circuit DB1 is a pulse width modulation circuit, but the disclosure is not limited thereto, and the led driving circuit 10 and the first pulse circuit DB1 therein may also include other driving circuits with different numbers of transistors and capacitors, for example, the following embodiments include driving circuits with pulse width modulation circuits and pulse width modulation circuits.
Fig. 4 is a schematic circuit diagram of a first pulse circuit and a second pulse circuit according to an embodiment of the invention. Referring to fig. 2, the first pulse circuit DB1 in the led driving circuit 20 is a Pulse Amplitude Modulation (PAM) circuit, and the second pulse circuit DB2 is a Pulse Width Modulation (PWM) circuit.
As shown in the drawing, the first pulse circuit DB1 includes a first transistor T1, a second transistor T2, a first capacitor C1, a third transistor T3, and a fourth transistor T4. The first end of the first transistor T1 is coupled to the pulse amplitude modulation Data line data_pam, the second end of the first transistor T1 is coupled to the control end of the first driving transistor TD1, and the control end of the first transistor T1 is coupled to the first Scan line Scan1. The first end of the second transistor T2 is coupled to the power-off signal line PPO, the second end of the second transistor T2 is coupled to the fourth node N4, and the control end of the second transistor T2 is coupled to the first Scan line Scan1. One end of the first capacitor C1 is coupled to the fourth node N4, and the other end of the first capacitor C1 is coupled to the second end of the first transistor T1. The first end of the third transistor T3 is coupled to the fourth node N4, the second end of the third transistor T3 is coupled to the first node N1, and the control end of the third transistor T3 is coupled to the first light emitting signal source EM1. The first end of the fourth transistor T4 is coupled to the fifth node N5, the second end of the fourth transistor T4 is coupled to the power-off signal line PPO, and the control end of the fourth transistor T4 is coupled to the first light-emitting signal source EM1.
The second pulse wave circuit DB2 includes a fifth transistor T5, a sixth transistor T6, a second capacitor C2, a seventh transistor T7, an eighth transistor T8, a ninth transistor T9, a tenth transistor T10, and a third capacitor C3. The first end of the fifth transistor T5 is coupled to the PWM Data line data_pwm, the second end of the fifth transistor T5 is coupled to the fifth node N5, and the control end of the fifth transistor T5 is coupled to the second Scan line Scan2. The first end of the sixth transistor T6 is coupled to the fifth node N5, the second end of the sixth transistor T6 is coupled to the sixth node N6, and the control end of the sixth transistor T6 is coupled to the seventh node N7. One end of the second capacitor C2 is coupled to the scan signal line sweet, and the other end of the second capacitor C2 is coupled to the seventh node N7. The first end of the seventh transistor T7 is coupled to the seventh node N7, the second end of the seventh transistor T7 is coupled to the sixth node N6, and the control end of the seventh transistor T7 is coupled to the second Scan line Scan2. The first end of the eighth transistor T8 is coupled to the seventh node N7, the second end of the eighth transistor T8 is coupled to the reset signal line RES, and the control end of the eighth transistor T8 is coupled to the start signal line VST. The first end of the ninth transistor T9 is coupled to the sixth node N6, the second end of the ninth transistor T9 is coupled to the control end of the second driving transistor TD2 via the eighth node N8, and the control end of the ninth transistor T9 is coupled to the first light emitting signal source EM1. The first terminal of the tenth transistor T10 is coupled to the reset signal line RES, the second terminal of the tenth transistor T10 is coupled to the eighth node N8, and the control terminal of the tenth transistor T10 is coupled to the set signal line VSET. One end of the third capacitor C3 is coupled to the reset signal line RES, and the other end of the third capacitor C3 is coupled to the eighth node N8.
In the present embodiment, the led driving circuit 20 is a sixteen-transistor three-capacitor (16T 3C) driving circuit structure, the first pulse circuit DB1 is a pulse amplitude modulation circuit, and the second pulse circuit DB2 is a pulse width modulation circuit. The following embodiments will take the present embodiment as an example to describe each detection section in which the light emitting diode LED performs the sensing operation.
Fig. 5A to 5C are schematic diagrams illustrating a sensing operation of the led driving circuit according to an embodiment of the invention. Fig. 5A is a schematic diagram of a static detection zone, fig. 5B is a schematic diagram of a light-emitting zone, and fig. 5C is a schematic diagram of a dynamic detection zone according to an embodiment of the present invention.
As shown in fig. 5A, when the light emitting diode LED has not yet operated for light emission, the light emitting diode driving circuit 20 may perform a static detection, and in a static detection interval, the first light emitting signal source EM1, the first pulse wave circuit DB1 and the first sensing gate signal line SG1 respectively transmit control signals to turn on the first light emitting control transistor TEM1, the first driving transistor TD1 and the first sensing transistor TS1, and the second light emitting signal source EM2, the second pulse wave circuit DB2 and the second sensing gate signal line SG2 respectively turn off the second light emitting control transistor TEM2, the second driving transistor TD2 and the second sensing transistor TS 2. At this time, the current I1 flows from the first voltage source VDD to the first sensing signal source VS1 through the first light emitting control transistor TEM1, the first driving transistor TD1 and the first sensing transistor TS1, and by detecting the current I1 flowing through the first sensing transistor TS1, the current I1 can be statically detected before the light emitting diode LED is turned on, and is compensated according to the actual detection result, so that when the light emitting diode LED starts to operate, the compensated current can make the light emitting diode LED achieve the required light emitting effect.
The static detection interval is a time when the LED is not formally turned on, and is mainly a pre-detection time before the LED driving circuit 20 is started, and the static detection is not performed before the frame of each display. Therefore, when the LED is in the display frame driving state of the display screen, the LED driving circuit 20 drives the LED to emit light and enters the light emitting section of each display screen, and in order to detect the amount of electricity actually passing through the LED during the light emitting section, and further compensate, it is necessary to perform dynamic detection during the light emitting period.
As shown in fig. 5B, when the light emitting diode LED starts to operate on the screen, the light emitting diode driving circuit 20 drives the light emitting diode LED to emit light, and in the light emitting section, the first light emitting signal source EM1 and the first pulse wave circuit DB1 transmit control signals to turn on the first light emitting control transistor TEM1 and the first driving transistor TD1, and the second light emitting signal source EM2 and the second pulse wave circuit DB2 transmit control signals to turn on the second light emitting control transistor TEM2 and the second driving transistor TD2, respectively. In the light emitting interval, the first sensing gate signal line SG1 turns off the first sensing transistor TS1, the second sensing gate signal line SG2 turns off the second sensing transistor TS2, and the current I2 flows from the first voltage source VDD to the second voltage source VSS through the first light emitting control transistor TEM1 and the first driving transistor TD1, and then flows along the light emitting diode LED, the second driving transistor TD2 and the second light emitting control transistor TEM2. The light emission control transistor LED is turned on by the passing current I2, and at this time, the current I2 does not flow to the sensing circuit because the first sensing transistor TS1 and the second sensing transistor TS2 are turned off.
In the light emitting interval, the first light emitting signal source EM1 and the second light emitting signal source EM2 respectively turn on the first light emitting control transistor TEM1 and the second light emitting control transistor TEM2 to make the current I2 pass, the pulse amplitude modulation circuit of the first pulse wave circuit DB1 controls the magnitude of the current I2 by driving the first driving transistor TD1, and the pulse width modulation circuit of the second pulse wave circuit DB2 controls the turn-on time by controlling the second driving transistor TD2 to further control the brightness of the light emitting control transistor LED, so as to achieve the desired display effect.
The LED driving circuit 20 may affect the actual light emitting state of the LED due to the process of the device itself, the circuit design, or the external environment, so that the LED driving circuit 20 dynamically detects the state of the LED during the light emitting interval to further compensate for the difference. As shown in fig. 5C, when the light emitting diode LED performs the light emitting operation, the light emitting diode driving circuit 20 can perform dynamic detection at the same time, and in the dynamic detection interval, the first light emitting signal source EM1 and the second light emitting signal source EM2 turn off the first light emitting control transistor TEM1 and the second light emitting control transistor TEM2, respectively, and the second pulse wave circuit DB2 also turns off the second driving transistor TD2. The first sensing gate signal line SG1 of the sensing circuit SB controls the first sensing transistor TS1 to be turned on and the second sensing gate signal line SG2 controls the second sensing transistor TS2 to be turned on, and at this time, the current I3 flows from the first sensing signal source VS1 to the second sensing signal source VS2 through the first sensing transistor TS1, the light emitting diode LED and the second sensing transistor TS2, and by detecting the state of the current I3, the actual light emitting state of the light emitting diode LED is detected, and then necessary compensation is performed on the driving circuit to achieve the required light emitting display effect.
Fig. 6 is a schematic waveform diagram of a driving circuit of an led according to an embodiment of the invention. The display panel may include n rows of display pixels, each row of display pixels drives a plurality of leds in the row according to the scan signal, and the waveforms of the operation of the led driving circuit 20 of fig. 4 are shown.
Firstly, in a static detection interval, a first light emitting control transistor TEM1 and a first sensing transistor TS1 are turned on by a control signal transmitted by a first light emitting signal source EM1 and a first sensing gate signal line SG1, and a current flows through the first light emitting control transistor TEM1, the first driving transistor TD1 and the first sensing transistor TS1 from a first voltage source VDD, so that by detecting the current flowing through the first sensing transistor TS1, static detection can be performed before the light emitting diode LED is turned on, the actual driving state of the driving circuit is confirmed, and the detection result is compensated, so that when the light emitting diode LED starts to operate, the compensated driving circuit can enable the light emitting diode LED to achieve the required light emitting effect.
When the display panel starts to display a picture, the panel scans line by line to drive the light emitting diodes LED in each pixel row, and as shown in the figure, the reset signal line RES resets the second pulse wave circuit PB2, the start signal line VST transmits the start control signal, and the first pulse wave circuit DB1 and the second pulse wave circuit DB2 receive the drive control signal and the set signal line VSET transmits the set signal. Then, after the first light emitting signal source EM1 and the second light emitting signal source EM2 transmit the control signal to turn on the first light emitting control transistor TEM1 and the second light emitting control transistor TEM2, the current is LED to light each pixel in the n-th row of pixels. The scan signal line sweet controls the second pulse circuit PB2 to determine the time of the first Pulse Width Modulation (PWM) light emission, and then the setting signal transmitted by the next setting signal line VSET starts the second pulse width modulation light emission, and so on.
In the present embodiment, each frame includes three light emitting intervals controlled by pwm signals, but the disclosure is not limited thereto, and the light emitting intervals included in each frame can be adjusted according to the display requirement. In these light emitting intervals, the light emitting driving circuit 20 can perform dynamic detection, and after the light emitting interval of the third pulse width modulation signal, the first sensing gate signal line SG1 and the second sensing gate signal line SG2 simultaneously turn on the first sensing transistor TS1 and the second sensing transistor TS2, at this time, the first light emitting control transistor TEM1 and the second light emitting control transistor TEM2 are turned off, and the current flows from the first sensing signal source VS1 to the second sensing signal source VS2 through the first sensing transistor TS1, the light emitting diode LED and the second sensing transistor TS 2. By detecting the state of the passing current, the state of the actual passing electric quantity of the light emitting diode LED can be dynamically detected while the light emitting interval is operated, compensation is performed for the detection result, for example, when uniformity problems occur, the control table of pulse wave amplitude modulation is adjusted, or when the pixel is affected by temperature, the control signal of pulse wave amplitude modulation is adjusted to perform corresponding compensation, so that the whole display panel can meet the requirement of a display picture, and the display effect cannot be affected by the variations.
In contrast to the led driving circuit of the present disclosure, which can perform dynamic detection during a normal driving light-emitting period, the driving circuit can still detect an actual voltage state of the led during the light-emitting period, and can compensate for variations generated during the operation period in real time, thereby not affecting the quality of the display screen.
Please refer to fig. 7A to 7C, which are schematic diagrams of a dynamic detection interval according to an embodiment of the present invention. Fig. 7A is a diagram illustrating a relationship between a dynamic detection interval and a frame according to an embodiment of the present invention, fig. 7B is a schematic diagram illustrating adjustment of the frame, and fig. 7C is a schematic diagram illustrating dispersion of the dynamic detection interval. As described in the foregoing embodiments, the dynamic detection section may perform the detection of the light emitting diode in the light emitting section, for example, the dynamic detection is performed after three light emitting sections of the pwm light emitting in the frame, but the detection section to perform the dynamic detection may be larger than the interval of the original light emitting section according to the number of the detection sections, so different detection modes may be used when performing the dynamic detection section, which are described as follows.
As shown in fig. 7A, the frame time of an original display frame of the led driving circuit includes three light emitting intervals of pwm light emission, and if dynamic detection is started after the third light emitting interval, the performed dynamic detection interval will exceed the original frame time to affect the display of the next display frame. Therefore, in the present embodiment, the dynamic detection section for dynamic detection occupies the light emitting section of the original third pwm light emission, and the original third light emitting time is used as the dynamic detection section for detecting the led status. Because the display result is affected by occupying the light-emitting interval, the detection mode is suitable for a specific detection frame. The number and sequence of occupied light-emitting intervals can be adjusted according to the requirement of dynamic detection, and is not limited to the third light-emitting interval in the embodiment.
As shown in fig. 7B, similar to the foregoing embodiment, the light emitting diode driving circuit includes a plurality of light emitting sections at the frame time of the display frame, and performing dynamic detection after the light emitting sections affects the display of the next display frame. Unlike the previous embodiment, the light emitting section is occupied in this embodiment. The LED driving circuit prolongs the frame time of the frame picture, so that the frame time is enough to finish the whole dynamic detection, namely, the frame time of the display picture is adjusted according to the dynamic detection interval. The detection mode is also suitable for specific detection frames, and the frame time is dynamically adjusted when the detection frames are executed to complete the operation of dynamic detection.
As shown in fig. 7C, the dynamically detected scans may be distributed among different display frames. Since the dynamic detection section required for completing the dynamic detection of the entire surface cannot be completed in the interval of the light emission section, the dynamic detection section is dispersed into different display frames. For example, dynamic scanning in the first frame time is started after the third light-emitting interval, the scanned pixel rows are only partial pixel rows, and dynamic scanning in the subsequent pixel rows is continued after the three light-emitting intervals in the second frame time are passed. The mode of dispersing dynamic scanning interval can maintain the original lighting interval and can not influence the display of normal display frames.
The foregoing is by way of example only and is not intended as limiting. Any equivalent modifications or variations to the present invention without departing from the spirit and scope of the present invention shall be included in the appended claims.
Claims (13)
1. A light emitting diode driving circuit, comprising:
the first pulse circuit is coupled to a data line and a scanning line, the output end of the first pulse circuit is coupled to the control end of a first driving transistor, the first end of the first driving transistor is coupled to a first node, and the second end of the first driving transistor is coupled to a second node;
a first light emitting control transistor, a first end of which is coupled to a first voltage source, a second end of which is coupled to the first node, and a control end of which is coupled to a first light emitting signal line;
the first end of the light-emitting diode is coupled to the second node, the second end of the light-emitting diode is coupled to a third node, wherein the first end of the light-emitting diode is an anode end, and the second end of the light-emitting diode is a cathode end;
the sensing circuit comprises a first sensing transistor and a second sensing transistor, wherein the second end of the first sensing transistor is coupled with the second node, the control end of the first sensing transistor is coupled with a first sensing grid signal line, the second end of the second sensing transistor is coupled with the third node, and the control end of the second sensing transistor is coupled with a second sensing grid signal line; and
the first end of the second light-emitting control transistor is coupled to the third node, the second end of the second light-emitting control transistor is coupled to a second voltage source, and the control end of the second light-emitting control transistor is coupled to a second light-emitting signal line.
2. The led driving circuit of claim 1, further comprising a second pulse circuit coupled to the data line and the scan line, wherein an output terminal of the second pulse circuit is coupled to a control terminal of a second driving transistor, a first terminal of the second driving transistor is coupled to the third node, and a second terminal of the second driving transistor is coupled to the first terminal of the second light-emitting control transistor.
3. The led driving circuit of claim 2, wherein the first pulse circuit comprises a pulse amplitude modulation circuit coupled to a pulse amplitude modulation data line and the scan line, and the second pulse circuit comprises a pulse width modulation circuit coupled to a pulse width modulation data line and the scan line.
4. The led driving circuit of claim 3, wherein the pulse amplitude modulation circuit comprises:
a first transistor, a first end of the first transistor is coupled to the pulse amplitude modulation data line, a second end of the first transistor is coupled to the control end of the first driving transistor, and the control end of the first transistor is coupled to the scanning line;
a second transistor, a first end of the second transistor is coupled to a power-off signal line, a second end of the second transistor is coupled to a fourth node, and a control end of the second transistor is coupled to the scan line;
one end of the first capacitor is coupled to the fourth node, and the other end of the first capacitor is coupled to the second end of the first transistor;
a third transistor, a first end of the third transistor is coupled to the fourth node, a second end of the third transistor is coupled to the first node, and a control end of the third transistor is coupled to the first light-emitting signal source; and
the first end of the fourth transistor is coupled to a fifth node, the second end of the fourth transistor is coupled to the power-off signal line, and the control end of the fourth transistor is coupled to the first light-emitting signal source.
5. The led driving circuit of claim 4, wherein the pwm circuit comprises:
a fifth transistor, a first end of the fifth transistor is coupled to the pwm data line, a second end of the fifth transistor is coupled to the fifth node, and a control end of the fifth transistor is coupled to the scan line;
a sixth transistor, a first end of the sixth transistor is coupled to the fifth node, a second end of the sixth transistor is coupled to a sixth node, and a control end of the sixth transistor is coupled to a seventh node;
one end of the second capacitor is coupled to a scanning signal line, and the other end of the second capacitor is coupled to the seventh node;
a seventh transistor, a first end of the seventh transistor is coupled to the seventh node, a second end of the seventh transistor is coupled to the sixth node, and a control end of the seventh transistor is coupled to the scan line;
an eighth transistor having a first end coupled to the seventh node, a second end coupled to a reset signal line, and a control end coupled to a start signal line;
a ninth transistor, a first end of the ninth transistor is coupled to the sixth node, a second end of the ninth transistor is coupled to the control end of the second driving transistor through an eighth node, and a control end of the ninth transistor is coupled to the first light emitting signal source;
a tenth transistor having a first end coupled to the reset signal line, a second end coupled to the eighth node, and a control end coupled to a set signal line; and
and one end of the third capacitor is coupled to the reset signal line, and the other end of the third capacitor is coupled to the eighth node.
6. The led driving circuit of claim 2, wherein the first light emitting control transistor, the first sensing transistor and the first driving transistor are turned on and the second light emitting control transistor, the second driving transistor and the second sensing transistor are turned off to detect the current flowing through the first sensing transistor when the led driving circuit is in a static detection interval.
7. The led driving circuit of claim 2, wherein the first light emitting control transistor, the first driving transistor, the second light emitting control transistor and the second driving transistor are turned on and the first sensing transistor and the second sensing transistor are turned off when the led driving circuit is in a light emitting interval, and the led is turned on by passing a current.
8. The LED driving circuit as defined in claim 7, wherein the first light emitting control transistor, the second light emitting control transistor and the second driving transistor are turned off, and the first sensing transistor and the second sensing transistor are turned on to detect the current flowing through the first sensing transistor, the LED and the second sensing transistor when the LED driving circuit is in a dynamic detection interval.
9. The LED driving circuit according to claim 8, wherein the dynamic detection interval is performed while occupying the light-emitting interval in a frame of the display.
10. The LED driving circuit according to claim 8, wherein a frame time of each frame is adjusted according to the execution time of the dynamic detection interval.
11. The LED driving circuit according to claim 8, wherein the dynamic detection intervals are distributed among different frames.
12. The led driving circuit of claim 1, wherein the first pulse circuit comprises a pulse amplitude modulation circuit coupled to a pulse amplitude modulation data line and the scan line.
13. The led driving circuit of claim 12, wherein the pulse amplitude modulation circuit comprises:
a first transistor, a first end of the first transistor is coupled to the pulse amplitude modulation data line, a second end of the first transistor is coupled to the control end of the first driving transistor, and the control end of the first transistor is coupled to the scanning line;
a second transistor, a first end of the second transistor is coupled to a power signal line, a second end of the second transistor is coupled to a fourth node, and a control end of the second transistor is coupled to the scan line;
one end of the first capacitor is coupled to the fourth node, and the other end of the first capacitor is coupled to the second end of the first transistor; and
the first end of the third transistor is coupled to the fourth node, the second end of the third transistor is coupled to the first node, and the control end of the third transistor is coupled to the first light-emitting signal source.
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| TW110135530A TWI778810B (en) | 2021-09-24 | 2021-09-24 | Light emitting diode driving circuit |
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| CN114333665A (en) | 2022-04-12 |
| TW202314667A (en) | 2023-04-01 |
| TWI778810B (en) | 2022-09-21 |
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